Construction method for foundation pit support utilizing prefabricated large-diameter pipe pile

ABSTRACT

Provided is a construction method for foundation pit support utilizing prefabricated large-diameter pipe pile, through this method the pipe pile can be sunk into a hole being drilled. The method applies to a large-diameter pipe pile being sunk. All of components, such as the prefabricated capping beam configured to fix all pile heads and the prefabricated waist beam configured to secure the pile bodies, can ensure the excellent fixture of the pipe piles during the construction of the foundation pit. This method has a good retaining and protecting effect when applied to construction of a deep foundation pit requiring large-diameter pipe pile. It can reduce the environmental impact caused by waste soil and mud discharge in traditional cast-in-place construction, and the use of prefabricated components decreased the construction period and improved the construction efficiency.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority of Application No. 201910734619.8 filed in China on Aug. 9, 2019, under U.S.C. § 119, the entire contents of which are hereby incorporated by reference.

FIELD OF TECHNOLOGY

The following relates to a field of foundation pit construction, in particular, a construction method for foundation pit support utilizing prefabricated large-diameter pipe pile.

BACKGROUND

The development and utilization of underground space generally requires the temporary support structure, so foundation pit engineering is very common in engineering construction. The foundation pit support construction not only play a role in retaining soil and water, but also requires cost under control, therefore, it is important to have such support structure with reasonable cost. The current support structure is mainly a cast-in-place structure, which generally has problems such as difficulty in ensuring construction quality, long construction period, and severe environmental pollution.

Compared with the cast-in-place structure of foundation pit support, a prefabricated support structure has the advantageous characteristics such as short construction period, low cost, being eco-friendly and reliable quality, thereby reduces energy consumption and construction waste, and shortens the construction period, and has a significant social and economic benefit. However, because the larger the diameter of the prefabricated pipe pile, the greater the resistance of sinking pipe pile, thus the diameter of the prefabricated supporting pipe pile constructed by the static pressure method or the hammer method is usually within 600 mm, and the support structure constituted by such prefabricated supporting pipe pile cannot be applied to the foundation pit engineering with deep excavation, as its relatively low anti-bending/anti-sheering performance due to the prefabricated supporting pipe pile with such relatively small diameter.

SUMMARY OF INVENTION

An aspect relates to a construction method for foundation pit support utilizing prefabricated large-diameter pipe pile, which is good for construction of a deep foundation pit requiring large-diameter pipe pile. It can reduce the environmental impact caused by waste soil and mud discharge in traditional cast-in-place construction, and the use of prefabricated components decreased the construction period and improved the construction efficiency.

Provided is a construction method for foundation pit support utilizing prefabricated large-diameter pipe pile, including the following steps:

Step 1. Drilling hole for pipe pile at a preset position, while sinking a prefabricated pipe pile into the hole;

Step 2. Repeating step 1 to obtain an array of the prefabricated pipe piles which each is buried in the respective hole drilled;

Step 3. Fixing each head of the prefabricated pipe piles on a prefabricated capping beam;

Step 4. Fixing a first horizontal support rod to the prefabricated capping beam at a side of foundation pit;

Step 5. Excavating the foundation pit surrounded by the prefabricated pipe piles; when the foundation pit reaches a preset depth, fixing a prefabricated waist beam to the pile bodies of the plurality of the prefabricated pipe piles, while fixing a second horizontal support rod to the prefabricated waist beam; and

Step 6. Removing part or all of prefabricated components when the foundation pit was reached to the desired bottom.

Comparing to the prior art, the advantage of the present invention is as follows:

The present invention discloses a construction method for foundation pit support utilizing prefabricated large-diameter pipe pile, through this method the pipe pile can be sunk into a hole being drilled. The method applies to a large-diameter pipe pile being sunk. All of components, such as the prefabricated capping beam configured to fix all pile heads and the prefabricated waist beam configured to secure the pile bodies, can ensure the excellent fixture of the pipe piles during the construction of the foundation pit. This method has a good retaining and protecting effect when applied to construction of a deep foundation pit requiring large-diameter pipe pile. It can reduce the environmental impact caused by waste soil and mud discharge in traditional cast-in-place construction, and the use of prefabricated components decreased the construction period and improved the construction efficiency.

Further, in the step 1, a retractable drill bit is configured below the prefabricated pipe pile, and is powered by a power supply device through a spiral drill rod set inside the prefabricated pipe pile; when the retractable drill bit works for drilling, the hole is produced for accommodating the prefabricated pipe pile.

Through this configuration, the drill bit can be used to drill a hole, while making it possible to sink the pipe pile into the hole. This method is convenient and fast, and improves the construction efficiency. After successfully sinking the pile, the drill rod and drill bit can be taken out with simply process.

Further, the step 1 includes:

Grouting a gap between the outer wall of the prefabricated pipe pile and the wall of the hole, in order to increase the effective contact area between the pipe pile and its surrounding soil.

Further, when using the retractable drill bit for drilling, an angle controller is used to adjust the drill rod and the prefabricated pipe pile to incline an angle, such that the inclined pile construction of large-diameter pipe pile can be accomplished, whereby the inclined pipe piles can improve the horizontal deformation resistance of the foundation pit.

Further, in the step 1, while the prefabricated pipe pile was sunk to the hole but not long enough, a quick joint is used for connecting the pipe pile to another prefabricated pipe pile such that the construction of sinking the prefabricated pipe pile can go on while the pipe pile for support purpose extends.

Further, the prefabricated capping beam includes a first capping beam and a second capping beam which both are disposed on both sides of each head of the prefabricated pipe piles, and a plurality of groove pairs are symmetrically set in opposite sides of both the first capping beam and the second capping beam, each groove pair corresponds to each head of the prefabricated pipe piles; the first capping beam and the second capping beam are connected by detachable bolts, whereby the heads of the prefabricated pipe piles can be secured well.

Further, the first horizontal support rod is fixed to the second capping beam through a first support rod joint, and the second horizontal support rod is fixed to the waist beam through a second support rod joint.

Further, a lock member is provided between the waist beam and the prefabricated pipe piles, and an expansion bolt penetrates through the prefabricated waist beam and the lock member to fix the prefabricated waist beam to the prefabricated pipe piles.

Further, brackets are configured underneath positions where the prefabricated pipe piles and the prefabricated waist beam are joined.

Further, in step 6, part or all of prefabricated components are gradually removed and recycled, for saving future cost and being eco-friendly.

BRIEF DESCRIPTION OF DRAWINGS

The embodiments of the present disclosure will be described hereinafter with reference to the following figures, wherein:

FIG. 1 is a flowchart of a construction method for foundation pit support utilizing prefabricated large-diameter pipe pile in accordance with an embodiment of the invention;

FIG. 2 depicts a schematic view of drilling construction in accordance with an embodiment of the invention;

FIG. 3 depicts a structurally schematic view of a quick joint among two pipe piles in accordance with an embodiment of the invention;

FIG. 4 depicts a structurally schematic view of a prefabricated capping beam in accordance with an embodiment of the invention;

FIG. 5 depicts a structurally schematically top view of a prefabricated waist beam in accordance with an embodiment of the invention;

FIG. 6 depicts a structurally schematically side view of a prefabricated capping beam in accordance with an embodiment of the invention;

FIG. 7 depicts a structurally schematic view of a vertical pipe pile support structure (fixed with horizontal support rod) in accordance with an embodiment of the invention, when the construction has been implemented;

FIG. 8 depicts a structurally schematic view of a vertical pipe pile support structure (fixed with tensile anchor) in accordance with an embodiment of the invention, when the construction has been implemented;

FIG. 9 depicts a structurally schematic view of an inclined pipe pile support structure (fixed with horizontal support rod) in accordance with an embodiment of the invention, when the construction has been implemented;

FIG. 10 depicts a structural schematic view of an inclined pipe pile support structure (fixed with a tensile anchor) in accordance with an embodiment of the invention, when the construction has been implemented.

LIST OF REFERENCE CHARACTERS

-   1 prefabricated pipe pile -   2 angle controller -   3 spiral drill rod -   4 retractable drill bit -   5 drilled hole -   6 gap between the outer surface of pipe pile and the wall of hole     drilled -   7 prefabricated capping beam -   71 first capping beam -   72 second capping beam -   9 bolt -   101 first horizontal support rod -   111 first support rod joint -   102 second horizontal support rod -   112 second support rod joint -   12 prefabricated waist beam -   13 U-shaped member -   14 expansion bolt -   15 bracket -   161 first tensile anchor -   162 second tensile anchor -   17 quick joint

DETAILED DESCRIPTION

The concept, the specific steps and the effect of the invention will be described hereinafter with reference to the figures and the embodiment, for understanding the invention easily.

As shown in FIG. 1, the embodiment discloses a construction method for foundation pit support utilizing prefabricated large-diameter pipe pile, including the following steps:

Step 1. Drilling hole for pipe pile at a preset position, while sinking a prefabricated pipe pile into the hole;

Specifically, as shown in FIG. 2, a retractable drill bit 4 is configured below the prefabricated pipe pile 1, and is powered by a power supply device through a spiral drill rod 3 set inside the prefabricated pipe pile 1. When the retractable drill bit 4 works for drilling, the hole 5 is produced for accommodating the prefabricated pipe pile 1, that is, using a drill bit set configured below the pipe pile to drill, and making it possible to sink the pipe pile into a hole drilled at the same time while drilling. This method is convenient and fast, and improves the construction efficiency. After successfully sinking the pile, the drill rod and drill bit can be taken out with simply process.

Specifically, as shown in FIG. 2, when using the retractable drill bit 4 for drilling, an angle controller 2 can be used to adjust the drill rod 3 and the prefabricated pipe pile 1 to incline 0°˜15° away from the vertical, such that the inclined pile construction of large-diameter pipe pile can be accomplished, whereby the inclined pipe piles can improve the horizontal deformation resistance of the foundation pit.

Specifically, as shown in FIG. 2, when the prefabricated pipe pile 1 was sunk, a gap 6 will exist between the wall of the hole drilled and the outer wall of the pipe pile. This gap can be grouted partially or fully according to the technical requirement, in order to increase the effective contact area between the pipe pile and its surrounding soil. Sometime, the gap is not grouted to reduce the lateral pressure to the pile from the surrounding soil.

Specifically, as shown in FIG. 3, while the prefabricated pipe pile 1 was sunk into the hole but not long enough, a quick joint 17 will be used for connecting the pipe pile 1 to another prefabricated pipe pile such that the construction of sinking the prefabricated pipe pile can be accomplished while the pipe pile for support purpose extends.

Step 2. Repeating step 1 to obtain an array of the prefabricated pipe piles which each is buried in the respective hole drilled.

Step 3. Fixing each head of the prefabricated pipe piles on a prefabricated capping beam.

Specifically, as shown in FIG. 4, the prefabricated capping beam 7 includes a first capping beam 71 and a second capping beam 72 which both are disposed on both sides of each head of the prefabricated pipe piles, and a plurality of groove pairs are symmetrically set in opposite sides of both the first capping beam 71 and the second capping beam 72, each groove pair corresponds to each head of the prefabricated pipe piles and can prevent the pipe pile from sliding around.

Specifically, the first capping beam 71 and the second capping beam 72 are connected by detachable bolts 9, whereby the heads of the prefabricated pipe piles can be secured well.

Step 4. Fixing a first horizontal support rod to the prefabricated capping beam at a side of foundation pit.

As shown in FIG. 4, the second capping beam 72 is configured at a side of foundation pit, that is, the foundation pit is excavated along the second capping beam 72. The first horizontal support rod 101 is fixed to the second capping beam 72 through a first support rod joint 111. Specifically, the second capping beam 72 is provided with an interface to connect with the first support rod joint 111 in which the first horizontal support rod 101 can be installed.

Step 5. Excavating the foundation pit surrounded by the prefabricated pipe piles. When the foundation pit reaches a preset depth, fixing a prefabricated waist beam to the pile bodies of the plurality of the prefabricated pipe piles, while fixing a second horizontal support rod to the prefabricated waist beam.

As shown in FIG. 5, the second horizontal support rod 102 is fixed to the prefabricated waist beam 12 through the second support rod joint 112, at a side of foundation pit.

Specifically, U-shaped members 13 are configured on the prefabricated waist beam 12 to receive the prefabricated pipe piles 1, where each U-shaped member 13 corresponds to each prefabricated pipe pile, and an expansion bolt 14 penetrates through the prefabricated waist beam 12 and the U-shaped member 13, to fix the prefabricated waist beam 12 to the prefabricated pipe pile 1. Specifically, the U-shaped member 13 is a curved steel member for secure the prefabricated pipe piles 1, and can be used to alleviate the contact stress concentration between the prefabricated waist beam 12 and the prefabricated pipe pile 1.

Specifically, in step 5, the brackets are further configured underneath the connect portion of the prefabricated pipe pile and the waist beam. Specifically, as shown in FIG. 6, a bracket 15 is configured underneath the support rod joint 112, the prefabricated waist beam 12 and the U-shaped member 13, to prevent all of those from falling down.

Specifically, both the first horizontal support rod 101 and the second horizontal support rod 102 may be replaced by a tensile anchor rod, for example, a first tensile anchor rod 161 and a second tensile anchor rod 162, such that it is a prefabricated pipe pile-anchor rod support system.

Step 6. Removing part or all of prefabricated components, including the prefabricated pipe pile, the prefabricated capping beam, the prefabricated waist beam, the U-shaped member, the expansion bolt, the bracket and the tensile anchor rod, when the foundation pit was reached to the desired bottom.

The finalized pipe pile support structure can be shown in FIG. 7 and FIG. 8.

Alternatively, if the angle controller is used to adjust the drilled hole and the pipe pile to incline a certain angle in step 1 to perform the construction of the inclined pile, the inclined pipe pile support structure is shown in FIG. 9 and FIG. 10.

When the construction for the foundation pit is completed and the main structure is constructed to a certain stage, part or all of the prefabricated components can be gradually recycled according to the actual and safe requirement, for saving future cost and being eco-friendly.

The prefabricated components described in this invention include all components, such as the prefabricated pipe pile, the prefabricated capping beam, the prefabricated waist beam, the U-shaped member, the expansion bolt, the bracket and the tensile anchor rod, in the foundation pit support structure, which are either concrete prefabricated components or steel structure welding standard modules, and can be made in advance in factory then assembled in the construction site.

The embodiment discloses a construction method for foundation pit support utilizing prefabricated large-diameter pipe pile, through this method the pipe pile can be sunk into a hole being drilled. The method applies to a large-diameter pipe pile being sunk. All of components, such as the prefabricated capping beam configured to fix all pile heads and the prefabricated waist beam configured to secure the pile bodies, can ensure the excellent fixture of the pipe piles during the construction of the foundation pit. This method has a good retaining and protecting effect when applied to construction of a deep foundation pit requiring large-diameter pipe pile. It can reduce the environmental impact caused by waste soil and mud discharge in traditional cast-in-place construction, and the use of prefabricated components decreased the construction period and improved the construction efficiency.

Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be apparent that any non-substantive, obvious alterations or improvement by the technician of this technical field according to the present invention may be incorporated into ambit of claims of the present invention. 

1. A construction method for foundation pit utilizing prefabricated large-diameter pipe pile, comprising: drilling a hole for pipe pile at a preset position, while sinking a prefabricated pipe pile into the hole; repeating said drilling the hole to obtain an array of the prefabricated pipe piles which each is buried in the respective hole drilled; fixing each head of the prefabricated pipe piles on a prefabricated capping beam; fixing a first horizontal support rod to the prefabricated capping beam at a side of foundation pit; excavating the foundation pit surrounded by the prefabricated pipe piles; when the foundation pit reaches a preset depth, fixing a prefabricated waist beam to the pile bodies of the plurality of the prefabricated pipe piles, while fixing a second horizontal support rod to the prefabricated waist beam; and removing part or all of prefabricated components when the foundation pit was reached to the desired bottom, wherein, during said drilling the hole, a retractable drill bit is configured below the prefabricated pipe pile, and is powered by a power supply device through a spiral drill rod set inside the prefabricated pipe pile; when the retractable drill bit works for drilling, the hole is produced for accommodating the prefabricated pipe pile, and an angle controller is used to adjust the drill rod and the prefabricated pipe pile to incline an angle.
 2. (canceled)
 3. The construction method of claim 1, the step 1 further includes: grouting a gap between an outer wall of the prefabricated pipe pile and an wall of the hole.
 4. (canceled)
 5. The construction method of claim 1, during said drilling the hole while the prefabricated pipe pile was sunk to the hole but not long enough, a quick joint is used for connecting the pipe pile to another prefabricated pipe pile such that the construction of sinking the prefabricated pipe pile can go on.
 6. The pile construction method of claim 1, wherein the prefabricated capping beam includes a first capping beam and a second capping beam which both are disposed on both sides of each head of the prefabricated pipe piles, and a plurality of groove pairs are symmetrically set in opposite sides of both the first capping beam and the second capping beam, each groove pair corresponds to each head of the prefabricated pipe piles; the first capping beam and the second capping beam are connected by detachable bolts.
 7. The construction method of claim 6, wherein the first horizontal support rod is fixed to the second capping beam through a first support rod joint, and the second horizontal support rod is fixed to the waist beam through a second support rod joint.
 8. The construction method of claim 1, wherein a lock member is provided between the waist beam and the prefabricated pipe piles, and an expansion bolt penetrates through the prefabricated waist beam and the lock member to fix the prefabricated waist beam to the prefabricated pipe piles.
 9. The construction method of claim 8, wherein brackets are configured underneath positions where the prefabricated pipe piles and the prefabricated waist beam are joined.
 10. The construction method of claim 1, wherein during said removing part or all of prefabricated components, part or all of prefabricated components are gradually removed and recycled. 